1. Field of the Invention
The present invention relates to a special effect generation system wherein there is provided, between a taking lens in an image pickup system and an image receiving medium, a compact optical device for reflecting a light beam having an optical member which forms a part of the optical device and is displaced to provide a scene with an interesting effect.
2. Description of the Prior Art
There has been a great demand in preparing television programming to provide a so-called special effect in an image pickup system which, for example, includes continuously rotating an image or inventing the direction of the image (either laterally or longitudinally).
To rotate image in preparing the programming for a monochromatic system, as shown in FIGS. 1 and 2, an inversion prism 4 can be attached in front of a taking lens 3 and an image pickup tube 2 which together form a camera 1 so that the image is rotated two revolutions during each revolution of the prism. Thus, as shown in FIG. 1, a special effect is generated by rotating an original image at increments of 45.degree. from position (a) to position (i).
In this case, however, since one inversion prism is used and hence the number of reflections of the light beam is odd, the generated image is inverted laterally. In order to correct it to a normal image it is necessary to modify an electric circuit in the camera device.
In recent years, a color system camera has been extensively used and, as shown in FIG. 3, such a camera 1 comprises a three-color split prism 5 and three image pickup tubes, i.e. a red image pickup tube 6a, a green image pickup tube 6b and a blue image pickup tube 6c. Furthermore a zooming lens having a large aperture has been commonly used as a taking lens. Accordingly it is not practical from the viewpoint of handling to mount the inversion prism in front of the taking lens. That is, a prism compatible with a large aperture zooming lens would be a huge one and hence not only the manufacture of the prism is difficult but also camera working would be difficult and the necessary modification of the electric circuit of the three image pickup tubes is also difficult. Accordingly this approach is not practical.
Another special effect of inverting the direction of the image (either longitudinally or laterally) has been effected in preparing a monochrome system programming by inverting the beam scan of the image pickup tube by electronic means. However in a present day color camera having three color image pickup tubes, such an approach is difficult to practice because of the problem of registration of the three image pickup tubes.
As a result, heretofore, even discrete rotation of the image has not been realized, which imposes a serious restriction on program 1 preparation.